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Problems in Environmental Impact Assessment

Scope, Benefits and Problems in Environmental Impact Assessment

The study of EIA effectiveness shows a number of difficulties and constraints, generally although not universally applicable, that continue to prevent and hinder EIA from consistently delivering these advantages and benefits:
Environmental Impact Assessment

What is Environmental Impact Assessment and its Objectives

An environment impact Assessment is an event or effect, which results from a prior event. It can be described as the change in an environmental parameter, over a specific period and within a defined area, resulting from a particular activity compared with the situation which would have occurred had the activity not been initiated.
Types of Activated Sludge Process

Types of Activated Sludge Process - Plug Flow, Complete Mix, SBR

In CMAS, mixing of tank contents is sufficient so that ideally concentrations of mixed-liquor constituents, soluble substances (COD, BOD, NH4-N), and colloidal and suspended solids do not vary with location in aeration basin. Plug Flow involves relatively long and narrow aeration basins so that concentration of soluble substances and colloidal and suspended solids
Microbial Metabolism in Biological Waste Water Treatment

Microbial Metabolism in Biological Waste Water Treatment

Carbon and Energy Sources for Microbial Growth: Organism must have sources of energy, carbon for synthesis of new cellular material, and inorganic elements (nutrients) such as nitrogen, phosphorus, sulfur, potassium, calcium and magnesium; Carbon Sources: Organisms that use organic carbon for formation of new biomass are called heterotrophs; Organisms that derive cell carbon from carbon dioxide are called autotrophs

Biological De-Nitrification Process in Waste Water Treatment System

Biological reduction of nitrate to nitric oxide, nitrousoxide, and nitrogen gas. Involves both nitrification and denitrification. Biological nitrogen removal (BNR) is more cost effective and used more often as compared to ammonia stripping, breakpoint chlorination and ion exchange; BNR is used in wastewater treatment where: there are concerns for eutrophication;
Nitrification Process

Biological Nitrification Process in Waste Water Treatment System

Total concentration of organic and ammonia nitrogen in municipal wastewater in the range 25‐ 45 mg/L as nitrogen based on flowrate of 450 L/capita.d (120 gal/capita.d). With limited water supplies, total nitrogen in excess of 200 mg/L as N measured in domestic wastewater. Drinking water maximum MCL for nitrate nitrogen is 45 mg/L as nitrate or 10
Sources of Drinking Water

Sources of Drinking Water

Streams, rivers and lakes are the major sources of surface waters. Usually these sources fulfill the requirements of municipal supplies. Water in these sources originates partly from groundwater outflows and partly from rainwater which flows over the terrestrial areas into the surface water bodies. Outflows from groundwater brings in, the dissolved solids.
Disinfection of Water

What is Disinfection and Methods of Disinfection of Water

In the water treatment processes, pathogens & other organisms can be partly physically eliminated through coagulation, flocculation, sedimentation, & filtration, in addition to the natural die-off. After filtration, to ensure pathogen free water, the chemical addition of chlorine (so called chlorination), rightly or wrongly, is most widely used for disinfection of drinking water
Chemical Characteristics of Sewage

Chemical Characteristics of Sewage - BOD, COD, Nutrients, DO

In sanitary sewage about 75 % of suspended solids and 40% of filterable solids are organic. These solids are derived from both animals, plant and humans. Organic compounds usually consist of C; H; O; N along with S; P and Iron. The organic substances found in sewage are Protein (40-60%); Carbohydrates (25-50%), fats and oils (10%). Along with these organic
Physical Characteristics of Sewage

Physical Characteristics of Sewage

Following are the detailed physical characteristics of Sewage: Temperature, Color, Odor, Solids, Total Solids, Total suspended Solids, Fixed and Volatile Solids. Oxygen is less soluble in warm water, while some species of aquatic life population increases with temperature causing more demand of oxygen and result in depletion of dissolved oxygen in summer.

Types of Grit Chambers in Waste Water Treatment

Check the SLR (1200-1700 m3/m2-day) and Vs (≥ 0.01 m/sec). Grit produced is about 1.5 ft3/ML of wastewater flow. Add to depth {1ft FB + grit}... Assume a depth (D = 08-15 ft), determine the surface area of the basin. And check the SLR (1200-1700 m3/m2-day)... The amount of grit produced is about 1.5 ft3/ML of wastewater flow. Add suitable depth from

Advantages & Disadvantages of Comminutors

Elimination of extra steps and problems involved in the excavation of the disposals of screening (screened material) Often difficult to dispose highly polluted screenings - In USA if buried, 6 inches of cover material should be used

Definitions in Waste Water Treatment

It is the measure of the settleability and compatibility of sludge and is made from a laboratory column setting test. The sludge volume index is defined as ‘the volume in mm occupied by 1 gm of sludge after it has settled for a specified period of time’ generally ranging from 20 min to 1 or 2 hr in a 1 – or 2-l cylinder.

What is the Composition of Wastewater?

A typical solids analysis of wastewater, of the total solids, 50% is dissolved, 50% suspended. Of the suspended solids, 50% will settle. Industrial activity changes the composition of wastewater, often introducing toxic substances such as chromium and cadmium from plating operations. The typical composition of wastewater based on strength. The important characteristics

Food to Microorganisms Ratio (F/M)

A parameter of organic loading rate in the design aerated sludge parameter in the design of Trickling Filter in organic loading rate = kg of BOD / m3-d

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